1. Field of the Invention
The present invention relates generally to coaxial cable connectors, couplings and fittings such as barrel connectors. More particularly, the present invention relates to an improved conductive, contact tube construction for barrel connectors and similar devices that facilitates an extremely dependable, wide-band connection. Known prior art is classified in United States Patent Class 439, Subclasses 406, 578, 654, 852, and 856.
2. Description of the Related Art
Popular cable television systems and satellite television receiving systems depend upon coaxial cable for distributing signals. As is known in the satellite TV arts, coaxial cable in such installations is terminated by F-connectors that threadably establish the necessary signal wiring connections. The ubiquitous F-connector forms a “male” connection portion that fits to a variety of threaded receptacles, forming the “female” portion of the connection. Barrel connectors, for example, have a pair of female terminal ports, one on each end, and they join two F-connector-borne cables together.
F-connectors have numerous advantages over other known fittings, such as RCA, BNC, SMA, and PL-259 connectors, in that no soldering is needed for installation, and costs are reduced as parts are minimized. For example, with an F-connector, the center conductor of a properly prepared coaxial cable fitted to it forms the “male” portion of the receptacle connection, and no separate part is needed. A wide variety of F-connectors are known in the art, including the popular compression type connector that aids in rapid assembly and installation. Hundreds of such connectors are seen in U.S. Patent Class 439, particularly Subclass 578.
However, the extremely high bandwidths and frequencies distributed in conjunction with modern satellite installations necessitates a variety of strict quality control factors. For example, the electrical connection established by the F-connector must not add electrical resistance to the circuit. It must exhibit a proper surge impedance to maintain a wide bandwidth, in the order of several Gigahertz. Numerous physical design requirements exist as well. For example, connectors must maintain a proper seal against the environment, and they must function over long time periods through extreme weather and temperature conditions. Requirements exist governing frictional insertion and disconnection or withdrawal forces as well. Importantly, since a variety of coaxial cable diameters exist, it is imperative that satisfactory F-connectors function with differently sized cables, such as RG-6 and RG-59 coaxial cables that are most popular in the satellite television art.
The foregoing F-connector considerations relate directly to the structure of the “female” sockets or receptacles to which the F-connectors are fitted. The “female” half of the junction must compliment the F-connector design imperatives. High bandwidth must be maintained through the junction, and reliable and effective impedance control is necessary. The socket, for example, must not exhibit an impedance discontinuity that can effect bandwidth.
Common receptive sockets to which F-connectors are fitted typically include some form of coaxial tube disposed concentrically within the fitting proximate to and concentric with the threaded input socket. The innermost conductor of the coaxial cable (i.e., that forms the “male” end of the connection that projects outwardly from the front of the F-connector) is electrically coupled to the tube when the F-connector is installed. A proper electrical contact must be formed at the latter juncture, internally of the mated connector elements. A variety of design constructions have been proposed for insuring such a connection.
For example, U.S. Pat. No. 4,128,293 issued Dec. 5, 1978 provides enhanced connections with an elongated metallic band having a plurality of substantially parallel fingers. One end of each finger is attached to and integral with the band. The fingers provide a large surface area for electrical contact.
U.S. Pat. No. 4,447,108 issued May 8, 1984 discloses an improved socket for electrical connectors defined by twisting of a cylindrical inner sleeve. Slots arranged on the cylindrical surface of the sleeve are inclined with respect to the longitudinal sleeve axis. The shape of the slots contributes to correct sleeve deformation in response to twisting.
U.S. Pat. No. 4,550,972 issued Nov. 5, 1985 discloses a formed contact socket with circumferentially continuous rings at pin receiving ends for enhancing electrical contact. An intermediate portion of the socket comprises beams which have ends integral with the rings. Inwardly formed spherical bosses are provided on the rings which engage a pin upon movement of the pin into the socket. The bosses are spaced along the axis of the socket and are encountered sequentially during axial movements of the pin into or out of the receptive socket.
U.S. Pat. No. 4,750,897 issued Jun. 14, 1988 discloses a contact apparatus with at least one segmented body formed by bars separated from each other by slots and having a curved central area. The bars have the form of a three-dimensional curve. In their end areas, the bars possess a section curved in the opposite sense to said curved central area.
U.S. Pat. No. 4,840,587 issued Jun. 20, 1989 discloses a female contact that receives a pin contact from an F-connector. Areas establishing electrical contact with the pin contact upon insertion are arranged at least approximately according to a family of straight generatrices of a hyperboloid of revolution of one branch. The composite female contact comprises a proper elastic contact element consisting of a cylindrical sleeve provided with through slots on its surface and inclined with respect to the longitudinal axis of the sleeve, which is deformed by twisting according to a predetermined angle and directed in the sense of inclination of the slots.
U.S. Pat. No. 5,667,409 issued Sep. 16, 1997 discloses a barrel connector for use with F-connectors that includes a pair of opposite “female” ends. A tubular, center conductor tube includes plural, inwardly punched contact points defined on the tube ends. The contacts firmly abut the central wire of coaxial cable terminating in an F-connector. The tube is constrained within a larger diameter housing with spaced sleeves. The material of the holes is punched inwardly, but is not removed from the tube. The contact component thus formed comprises a pair of inclined planes extending towards the interior of each end of the tube.
U.S. Pat. No. 5,863,226 issued Jan. 26, 1999 discloses a connector for coaxial cable including a tubular contact fitted between two insulating sleeves. The contact member is made from sheet material by curling. Ends of the contact member are not joined together, and a narrow slit is defined between them. When a wire core with a diameter of between 1.2 to 1.3 mm, i.e., as with an F-type coaxial connector, is inserted into the contact member, the contact member is stretched open to achieve greater resilience.
U.S. Pat. No. 6,113,431 issued Sep. 5, 2000 provides an F-port coaxial barrel connector. The connector body comprises threads on its opposite ends for receiving F-connectors, with a central hexagonal mounting nut. Fitted inside the containment hole is a first insulator sleeve and a second insulator sleeve, and clipped in between the first and second insulator sleeves is a tubular contact component. Lathe fabrication allows for a smooth and even finish on all flat surfaces and enables the assembly of the first insulator sleeve, the second insulator sleeve, and tubular contact component to be conveniently inserted into the containment hole, while preventing dislodging.
U.S. Pat. No. 6,065,997 issued May 23, 2000 discloses an analogous connector device for use with cable and satellite television installations, including an integrally formed housing, a contact member and an insulating tube fitted in an inner, through-hole of the housing. An annular groove is formed on an inner edge of one end of the housing and an engaging flange is formed at the other end of the housing. The insulating tube is disposed within the annular flange. The contact member is placed in the insulating tube which is fitted into the housing with the annular flange engaged with the annular groove.
U.S. Pat. No. 6,808,426 issued Oct. 26, 2004 also discloses a barrel connector for use with popular F-connectors. A conductive contact tube that is coaxially constrained within the connector by special end sleeves includes inwardly bent, clamping tabs for establishing electrical contract by grasping the coaxial cable center conductor when an F-connector is threadably fitted to the barrel connector.
U.S. Pat. No. 6,899,563 issued May 31, 2005 provides a coaxial cable connector with an internal transmission tube comprising four elastic strips at each of its two ends. The four elastic strips are disposed in the transmission tube in a bent manner, and each elastic strip is formed with a projecting plane and inclined planes. Side edges of the four elastic strips are joined to form a clamping end for inserting and connecting with a coaxial cable therein.
U.S. Pat. No. 7,252,560 issued Aug. 7, 2007 discloses a center conductor for use in a coaxial jack module.
Numerous other patents relating to electrical construction contact techniques exist, such as U.S. Pat. Nos. 3,317,887, 3,381,261, 3,678,451, 3,815,081, 3,861,776, 4,002,400, 4,298,242, 4,550,972, 6,186,841, 7,121,881, 7,387,548, and 7,442,080.